Companies that focus on the immediate breach remediation costs may be missing the big picture, and could be under-investing in security as a result.

Several studies have come out recently trying to get a handle on the total costs of a data breach, with a large variation in costs - from less than $1 million on average, to $6 million - based on the data sets and types of included costs.

But the actual numbers could be several times higher.

Take the Yahoo breach, for example, which could lead to a $1 billion drop in the company's value.